The United States had received intelligence reports regarding a possible terror attack in Glasgow against airport infrastructure or aircraft two weeks ago, a television channel report has said.
The American law enforcement officials had received the intelligence reports two weeks ago and it also warned that airports and aircraft in the Czech Republic could be the targets of Al-Qaeda, the ABC News said said quoting an unidentified law enforcement official.
The warnings were kept secret for operational reasons, according to officials.
In public, the White House and Homeland Security Secretary Michael Chertoff have continued to maintain they know of no specific or credible threats involving the United States, even though the intelligence reports specify US aircraft as possible targets.
An US official told ABCNews.Com that the intelligence reports led to the assignment of Federal Air Marshals on American aircraft flights into and out of both Glasgow and Prague.
Meanwhile, media reports spoke of the possibility of "sleeper cells" Britain being activated.
ABC News quoted counter terrorism analysts as saying that apparently coordinated attacks in Britain could be the work of a sleeper cell that could include as many as 20 individuals.
"You would need that many to pull off three different vehicle-borne explosions. The Brits simply are not ahead of this cell and they know it," one former CIA official, on condition of anonymity, told the network.
{{/usCountry}}"You would need that many to pull off three different vehicle-borne explosions. The Brits simply are not ahead of this cell and they know it," one former CIA official, on condition of anonymity, told the network.
{{/usCountry}}Adding to the intelligence failure, analysts said, is the fact that the driver of one of the failed car bombs had been arrested three years ago and released for lack of evidence.